docs: def to_file(self, destination, format='csv', csv_delimiter=',', csv_header=True):
      """Save the results to a local file in CSV format.
  
      Args:
        destination: path on the local filesystem for the saved results.
        format: the format to use for the exported data; currently only 'csv' is supported.
        csv_delimiter: for CSV exports, the field delimiter to use. Defaults to ','
        csv_header: for CSV exports, whether to include an initial header line. Default true.
      Raises:
        An Exception if the operation failed.
      """
      f = codecs.open(destination, 'w', 'utf-8')
      fieldnames = []
      for column in self.schema:
        fieldnames.append(column.name)
      if sys.version_info[0] == 2:
        csv_delimiter = csv_delimiter.encode('unicode_escape')
      writer = csv.DictWriter(f, fieldnames=fieldnames, delimiter=csv_delimiter)
      if csv_header:
        writer.writeheader()
      for row in self:
        writer.writerow(row)
      f.close()